English

The Filter Dichotomy and medial limits

Logic 2010-09-02 v1 Functional Analysis

Abstract

The \emph{Filter Dichotomy} says that every uniform nonmeager filter on the integers is mapped by a finite-to-one function to an ultrafilter. The consistency of this principle was proved by Blass and Laflamme. A function between topological spaces is \emph{universally measurable} if the preimage of %every open subset of the codomain is measured by every Borel measure on the domain. A \emph{medial limit} is a universally measurable function from P(ω)\mathcal{P}(\omega) to the unit interval [0,1] which is finitely additive for disjoint sets, and maps singletons to 0and ω\omega to 1. Christensen and Mokobodzki independently showed that the Continuum Hypothesis implies the existence of medial limits. We show that the Filter Dichotomy implies that there are no medial limits.

Keywords

Cite

@article{arxiv.1009.0065,
  title  = {The Filter Dichotomy and medial limits},
  author = {Paul B. Larson},
  journal= {arXiv preprint arXiv:1009.0065},
  year   = {2010}
}

Comments

8 pages

R2 v1 2026-06-21T16:07:49.195Z